This invention relates to anchoring tissue grafts.
An increasing number of surgical techniques are now performed arthroscopically. One type of arthroscopic procedure reconstructs the anterior cruciate ligament (ACL) in the knee. Several ACL reconstruction techniques are described in U.S. Pat. No. 5,139,520 (issued Aug. 18, 1992) (xe2x80x9cthe ""520 patentxe2x80x9d) and incorporated by reference.
When the ACL has ruptured and is nonrepairable, it is usually replaced in the knee using a substitute graft harvested from the patient or from a donor. The substitute ACL graft may be a portion of a patellar tendon having so called xe2x80x9cbone blocksxe2x80x9d at each end. A method and an apparatus for harvesting such a patellar tendon graft is described in U.S. Pat. No. 5,733,289 (issued Mar. 31, 1998) (xe2x80x9cthe ""289 patentxe2x80x9d) and incorporated by reference. Alternatively, an artificial graft formed from synthetic materials or from a combination of artificial and natural materials may be used and is sometimes referred to as a ligament augmentation device (LAD). The term xe2x80x9ctissue graftxe2x80x9d is used herein to encompass all of these tissue replacement items.
In general, the replacement tissue graft is implanted by securing one end of the tissue graft in a socket formed in a passage formed within the femur (i.e., femoral channel) and passing the other end of the graft through a passage formed in the tibia (i.e., tibial channel). Then, the graft is secured to the tibia adjacent to the tibial channel. Generally, sutures are used to affix each end of the tissue graft to a fastener (e.g., an interference screw or a post), which is then secured to the bone. Descriptions of these fasteners and methods of forming the passages through the tibia and femur are described in greater detail in the ""520 patent.
Another approach for affixing a tissue graft is described in U.S. Pat. No. 5,306,301, (issued Apr. 26, 1994) (xe2x80x9cthe ""301 patentxe2x80x9d) and incorporated by reference. The ""301 patent discloses using a fixation button to secure a tissue graft at the femoral cortex. The fixation button has an elongated shape and at least one pair of openings through which a suture may be passed and then tied off.
In this approach, the femoral channel has a portion having a first diameter sized to accommodate a bone block and a second portion having a smaller diameter through which the bone block cannot pass. By measuring the total length of the femoral channel and the length of the larger portion, the surgeon determines a xe2x80x9csuture spanxe2x80x9d for attaching the fixation button to the tissue graft.
The surgeon forms an opening in the bone block to be positioned in the femoral channel and threads an end of suture through it. The surgeon then ties the suture to the fixation button, providing the suture span between the button and the bone block. The fixation button and the tissue graft are then passed through the tibial and femoral channels until the graft is properly seated within the socket portion of the femoral passage and the fixation button is firmly seated against the femoral cortex. The tissue graft is then tensioned and anchored at its opposite end using a fixation screw secured within the tibia.
Still another approach for affixing a tissue graft is described in U.S. Pat. No. 5,769,894, (issued Jun. 23, 1998) (xe2x80x9cthe ""894 patentxe2x80x9d) and incorporated by reference. The ""894 patent describes a graft fixation member configured to allow the length of the suture between the fixation member and the graft to be adjusted and to maintain the adjusted length when the suture is secured to the graft fixation member.
An alternative to tying a suture to a fixation button is disclosed in PCT Application WO 99/47079 (published Sep. 23, 1999) (xe2x80x9cthe ""079 applicationxe2x80x9d) and incorporated by reference. The ""079 application discloses an apparatus and method for attaching a continuous loop of suture to a fixation button. Using a series of rollers, the continuous loop is formed from a strand of suture repeatedly coiling the suture through openings in a fixation button. In other examples, a continuous loop of suture may be formed without a fixation member. Continuous loops, both with and without fixation buttons attached, are available from Xiros Limited, Leeds, England, in several sizes. A surgeon selects the closest matching size for a given ACL reconstruction procedure. In other examples, a continuous loop of suture may be formed without a fixation member.
In an aspect, the invention features a method for securing a tissue graft within a bone passage. A graft fixation member comprising a closed-loop having a pair of opposing loop sections is provided and a first loop section of the closed loop is captured within the fixation member. An opposing second loop section of the closed loop is passed through an opening in the tissue graft and is secured to the fixation member.
In another aspect, the invention features a method of securing a tissue graft within a bone passage including providing a graft fixation member comprising a closed loop having a pair of opposing loop sections. A first loop section of the closed loop is captured within the fixation member. A bight is formed in the closed loop by passing an opposing second loop section of the closed loop through an opening in the tissue graft. The fixation member and the first loop section are passed through the bight in the closed loop to capture the tissue graft.
In another aspect, the invention features a method of securing a tissue graft within a bone passage including providing a first graft fixation member and a second graft fixation member and a closed loop having a pair of opposing loop sections. A first loop section of the closed loop is captured within the first graft fixation member and an opposing second loop section is passed through an opening in the tissue graft. A second loop section of the closed loop of suture is captured within the second graft fixation member.
One or more of the following features may also be included. The opening is formed in the tissue graft. The opening is formed in a bone block of the tissue graft. The opening is formed in a tendon of the tissue graft. The fixation member is passed through the bone passage. The fixation member through a bone passage in a tibia and then through a bone passage in a femur. The fixation member is first passed through a bone passage in a femur and then through a bone passage in a tibia. The fixation member is positioned to pass through the bone passage using a suture. The fixation member is positioned to pass through the bone passage using closure tape. The second loop section is captured within the second fixation member before the second loop section is passed through the opening in the tissue graft. Passing the second loop section through the opening in the tissue graft includes passing the second fixation member through the opening.
In another aspect, the invention features a device for securing a tissue graft within a passage within a bone. The device includes a member having an intermediate portion and an end portion. The end portion has a pair of arms extending from the intermediate portion and defining an open channel at the end portion. Each arm has an opening extending from a first side of the arm to a second side of the arm, the opening being sized to accommodate a strand of suture.
One or more of the following features may also be included. One or more openings pass through the intermediate portion of the member. The openings are cylindrical. The opening in each arm is cylindrical. The openings in each pair of arms occupy different positions on a common axis. The axis is transverse to the member. The pair of arms define a cylindrical portion of the channel having a diameter equal to the width of the channel. Each pair of arms define a cylindrical portion of the channel having a diameter greater than the width of the channel. The arms are shaped to pass through bone passage. The member is sized to pass through a bone passage. The member comprises a bio-compatible material. The member comprises titanium. The member comprises a bio-absorbable material.
Embodiments may have one or more of the following advantages. The closed loop may be manufactured and purchased separate from the fixation member. This allows the surgeon the flexibility to choose the correct size closed loop from several sizes available in the operating room without a fixation member on each size loop. In turn, the patient benefits from the reliability of the closed loop without the added cost of multiple fixation members. The closed loop is positively captured within the fixation member during implantation. The closed loop provides superior strength over single loops of tied suture or tape and does not extend a patient""s time under anesthesia while a surgeon forms multiple loops of suture or tape by hand. The closed loop may be pre-stressed during the manufacturing process to reduce its elasticity and increase its strength without accommodation for a fixation member.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.